The present invention relates to an apparatus for shifting a pair of printing cylinders mutually and relatively to the other, when the printing mode is switched from one printing mode to the other printing mode, in a rotary press adapted to perform printings of a plurality of different printing modes. Further, for a rotary press in which an intermediate mode, i.e. an impression throw off, is required, the invention relates to an apparatus of the kind described and capable of allowing a branching to such an intermediate mode.
The rotary presses capable of performing a plurality of printing modes to which the present invention is applied are:
(1) a rotary press capable of performing both of relief printing and relief offset printing (See FIGS. 1 to 3) and PA0 (2) an offset rotary press capable of performing both of satelite design printing and BB (blanket to blanket design) printing (See FIGS. 4 and 5).
These presses have the following common basic arrangement of cylinders. Namely, among the five cylinders including two plate cylinders 16 and 17, two printing or blanket cylinders 18 and 19, and one impression cylinder 20, the two plate cylinders 16 and 17 and the impression cylinder 20 are disposed at positions corresponding to apices of an equilateral triangle, and the blanket cylinders 18 and 19 are disposed between the impression cylinder 20 and the plate cylinders 16 and 17, respectively. It is possible to perform printings of a plurality of different printing modes, by bringing two blanket cylinders 18 and 19 into and out of contact with each other and with other cylinders 16, 17 and 20. The present invention is concerned with an apparatus for effecting the shifting and switching of these two printing cylinders 18 and 19 relatively to each other and to other cylinders.
The relationship between the positions of the cylinders and the printing modes from the view points of positions of two printing cylinders is as follows.
In the arrangement as shown in FIG. 1, the blanket cylinders 18 and 19 are in contact with the plate cylinders 16 and 17, respectively. The blanket cylinders are not in contact with each other. The impression cylinder 20 has been moved upward away from the blanket cylinders. This arrangement is for a relief printing. A monochromatic printing on both sides of paper and a double color printing on single side can be achieved by the paths of webs W1 and W2.
The arrangement as shown in FIG. 2 is substantially identical to that of FIG. 1 but the impression cylinder 20 has been moved downward into contact with the blanket cylinders. This arrangement is for a relief offset printing. A doubl color printing on single side of paper is performed with a path of web W3.
The arrangement as shown in FIG. 3 is characterized in that the blanket cylinders 18 and 19 are in contact with each other but are not of contact with the impression cylinder 20. This arrangement is for a relief offset printing. A monochromatic printing on one side of the paper is effected with a path of web W4.
FIG. 4 shows the arrangement of the printing cylinders in relation to other cylinders adopted when the printing machine is used for B-B offset printing, i.e. the same arrangement as that shown in FIG. 3. The path of web W5 is strictly identical to that W4 as shown in FIG. 3, and affords a monochromatic printing on both sides. Further, it is possible to effect a monochromatic printing on one side and double color printing on the other side, by bringing a third blanket cylinder 60 into contact with the impression cylinder 20 and a third plate cylinder 61 into contact with the third blanket cylinder 60, with a path of web W6.
FIG. 5 shows the arrangement of printing cylinders in relation to other cylinders, i.e. the same arrangement as that of FIG. 2, adopted when the printing machine is used for a satelite design offset printing. It is possible to effect a tricolor printing on one side with a path of web W7, by adding a third blanket cylinder 60 and a third plate cylinder 61 to the arrangement as shown in FIG. 2, as in the case of arrangement shown in FIG. 4.
From a view point of movements of printing cylinders, i.e. the blanket cylinders 18 and 19, the arrangement as shown in FIG. 1 is identical to that of FIG. 2, while the arrangement as shown in FIG. 5 is identical to that of FIG. 2. At the same time, the arrangement as shown in FIG. 4 is identical to that of FIG. 3, from the same point of view. Thus, the relative positions of the printing cylinders between which these cylinders are switched by the apparatus of the invention are the first position as shown in FIGS. 1, 2 and 5 and the second position as shown in FIGS. 3 and 4. In case of the B-B printing (FIG. 4) and the satelite design printing (FIG. 5), it is necessary to take a intermediate mode, i.e. a state of impression throw off as shown in FIG. 8. However, no impression throw off is required in the switching between the relief printing (FIG. 1) and relief offset printing (FIG. 2), and other relief offset printing (FIG. 3).
The above stated technical subject of switching of printing cylinders has been achieved conventionally by a method in which the shifting of the printing cylinders from one to the other positions is made via the intermediate mode, i.e. the state of impression throw off as shown in FIG. 8. This inconveniently requires two reciprocating motions of the actuator, as well as a conversion of fulcrum of power transmitting link at the intermediate mode. As a result, the conventional system requires a troublesome operation which may incur an error. It is considered that the above-stated conventional solution has been adopted because of the difficulty in achieving the large angular displacement of the eccentric sleeves required for the directly shifting of the printing cylinders only by one stroke of the actuator.
It is therefore an object of the invention to create and provide a switching apparatus between printing modes in printing cylinders of rotary press, in which the large angular displacements of eccentric sleeves, which is required for directly shifting the pair of printing cylinders from one to the other positions, can be effected safely, promptly and easily by a single stroke of actuator, thereby to overcome above stated problem of the prior art.
It is another object of the invention to create and provide a switching apparatus between printing modes in printing cylinders of rotary press, in which the intermediate mode, i.e. the impression throw off is provided not merely as a relaying position in the switching between one position and other position of the printing cylinders, but, rather, the switching to the intermediate mode is possible independently and branchingly from either of the first and second modes, after completion of the switching to either mode, so that it is possible to reset the cylinders to the cylinder arrangement under the use safely, promptly and easily, after the completion of the work which requires a shifting to the impression throw off.